The present invention relates to multijoint flexible therapeutic pads which act as heat exchangers for delivering thermal gradients to the knee, shoulder and other parts of the body.
Effectiveness of thermal therapy in post trauma and post surgical settings continues to engender a variety of thermal therapy systems. (The term xe2x80x9cthermal therapyxe2x80x9d for purposes of this document means therapy which induces hypothermia or hypothermia, cold or heat, to the body or a part of it, whether extradurally or otherwise.) The precise mechanics of thermal therapy remain the subject of debate and research. The literature indicates that cold therapy can, for instance, reduce swelling, inflammation, edema and ischemic damage due to vascular or arterial compromise. Cold therapy is also said as a general matter to aid in control and management of tissue hypoxia that can otherwise be a manifestation of impaired oxygen diffusion or compromised circulation. It also is generally recognized to reduce pain and reduce the need for pain relief medication.
Recent developments in thermal therapy systems include patient portable systems which employ a small ice chest connected to a flexible heat exchanger or thermal therapy pad via a pair of tubes. A pump, which may be located in the ice chest, supplies chilled fluid to an inlet port of the pad. An exhaust port connected to an exhaust tube carries the fluid, or a portion of it, in a return loop to the ice chest. Temperature within the pad may be regulated in a number of ways. A valve may be employed to control the flow rate in the pad inlet or exhaust, and/or to recirculate a portion of the exhaust fluid.
In physical therapy, as in many things, effectiveness of treatment is largely a function of convenience and comfort. Portable thermal therapy systems accordingly enjoy increased popularity to a major degree because their increased convenience promotes the patient""s actually adhering to the therapy program. Such systems, for instance, eliminate the need constantly to replenish an ice pack with a new supply of ice, endure the chore of a weighty and cumbersome ice pack on the knee or shoulder, and the added bother of interposing a towel, with its inevitable sogginess, to mediate between the freezing ice cubes and the skin. Conventional thermal therapy systems instead use a thinner, lighter, flexible pad with a reasonably but not overly cold temperature. The patient may carry the ice chest with its own battery pack in order to supply circulation of the chilled fluid to the pad, or when able to access an electrical outlet, rely on the power grid using a power converter.
Because efficacy of physical therapy and cold therapy in particular is largely a function of convenience, conventional thermal therapy systems present significant additional potential for improvement and design breakthroughs. Because patients tend to abandon the course of thermal therapy treatment if it is inconvenient or uncomfortable, it is critical to ensure that the flexible therapeutic pad of such systems is comfortable to the patient, promotes convenience, and is minimally intrusive to the patient""s flexibility and mobility. Patients will be inclined to discontinue the therapy if the pad, for instance, overly restricts mobility of the joint, must be continually reapplied, requires undue attention and readjustment, feels uncomfortable, or is otherwise cumbersome, awkward or inconvenient.
On another more immediate level, effectiveness of the heat transfer imparted by the flexible therapy pad may suffer if a thermal therapy pad becomes occluded as it is placed on the joint or as it flexes with the joint. Some conventional pads are shaped in a manner that causes internal blockage when placed on the joint or as the knee or shoulder flexes; such blockage restricts fluid flow in at least parts of the pads and thus deprives portions of the body surface of effective thermal therapy. Moreover, some conventional pads lose contact with areas of the skin when initially placed on the knee or shoulder or when the knee or shoulder is flexed and the pads fail effectively to conform to the body surface through the appropriate range of flexion. Accordingly, increased flexibility of the therapy pad must not be undertaken at the expense of effective heat transfer.
Previous flexible therapeutic pads employed in cold therapy systems recognize the value of a thinner pad per se but they generally adhere gratuitously to notions of symmetry. For instance, the pad disclosed in U. S. Pat. No. 5,086,771 issued Feb. 11, 1992 to Molloy and U. S. Pat. No. 5,417,720 issued May 23, 1995 to Mason, are symmetrical about their center axis. Although symmetry appeals intrinsically to the intellect, the present invention does not blindly bow to or adopt symmetry in flexible therapeutic pad topology. In that respect, U.S. Pat. No. 5,411,542 issued May 2, 1995 and U.S. Pat. No. 5,470,353 issued Nov. 28, 1995 to Jensen show asymmetrical thermal therapy pads, but in a way specifically tailored to the ankle and shoulder joint, respectively. Such specialized pads can provide comfort, convenience and more effective heat transfer through a better fit, but requiring separate pads for the ankle and shoulder presents added design, manufacturing, distribution, inventory and tracking expense because, among other things, a number of different pad designs must be supported throughout this entire chain rather than a single pad design which can accommodate various joints.
Conventional flexible therapeutic pads as described in the Mason and Molloy patents feature inlet and exhaust ports on the center line about which the pads are symmetrical. It is a given that the inlet and exhaust tubes to which the ports are connected must be oriented, for purposes of convenience, generally on the limb, such as for instance, either up the limb or down it, in order to avoid cantilevering the tubes into mid-air and subjecting them to physical interference, inconvenience, excessive wear and abuse. The axis of symmetry of the conventional multijoint pads being aligned with the tubes requires these conventional symmetrical pads to extend continuously and uninterrupted along the proximal/distal axis across the patella or shoulder joint. Flexure of the knee or shoulder causes buckling of such a pad along its center line. The buckling of such pads and concomitant failure effectively to conform to the limb as it flexes can not only cause internal occlusion or blockage within parts of the pad to obstruct fluid flow and render at least a part of the pad ineffectual for thermal therapy; it can also naturally separate the heat exchanger from the body to reduce effectiveness of the cold therapy, create discomfort, and introduce resistance to joint flexure and mobility.
Pads of the present invention, by contrast, feature at least two members which are adapted in shape to conform to body parts that surround the knee, shoulder or other joint, but which members are in fluid communication via a conduit whose centerline does not overlie the patella or the top of the shoulder, or which is not substantially centered on the patella as the joint flexes. Centering of the conduit to one side of the patella or top of the shoulder, the inventors have found, makes a substantial difference in providing flexible fit, form and function without compromise of effective fluid flow in all areas of the pad and consequent effectiveness of thermal therapy imparted by the pad. Positioning the conduit that connects these members may be carried out, for example, by introducing, according to the present invention, gaps, clefts or other peripheral discontinuities which could, for example and if desired (but not necessarily), overlie and intersect the limb proximal/distal axis in order to increase flexure of the pad without compromising other value properties.
The present invention also exploits the opportunity to optimize flow velocity at predetermined points within a flexible therapeutic pad, unlike conventional pads, in order to accentuate local heat transfer rate where appropriate. The inventors believe, and their experiences tend to show, that they can adjust and create flow restrictions at desired points within the pads in order to regulate local flow velocity and affect heat transfer rate where the knee or shoulder needs it. For instance, the inventors believe that increasing local flow velocity closer to the interior of the pad as a general matter can promote a greater heat transfer rate at the site of injury or surgery, with reduced heat transfer at the perimeter of the site. Such variable heat transfer rates can be particularly useful in applications where inflammation, edema, ischemia and/or swelling is local in nature.
The present invention provides flexible therapeutic pads which are adapted to accommodate the knee joint and the shoulder joint, together with other joints if desired. Like previous pads, they may be formed with a first layer of flexible material of a desired shape whose periphery is bonded, heat welded or otherwise joined to the periphery of a second layer of flexible material in order to form a heat exchanger which may be applied to the patient""s body. Other layers may be added, such as a foam layer, and a hook or loop layer for securing the pad to the body. An inlet port and an exhaust port feed a fluid or other thermal medium to the pad and remove it, respectively, in order to create the thermal differential which is applied to the pad/tissue interface in order to induce heat transfer. (The term xe2x80x9cheat transferxe2x80x9d means flow of thermal energy from hot to cold and, as part of that process, flow of lower thermal energy state from cold to hot. The term as used in this document contemplates any transfer or flow of thermal energy, or lack of it, to induce hypothermia or hypothermia extradurally or otherwise.)
Unlike previous multijoint flexible therapeutic pads, however, pads according to the present invention need not be symmetrical along their center line but instead can focus on providing at least two members each of which is adapted to conform to a part of the leg adjacent to the knee, or the arm or torso in the case of the shoulder. The members are in fluid communication with each other through at least one conduit whose center does not overlie the patella or the top of the shoulder, or which is not substantially centered on the patella or top of the shoulder as the joint flexes. Centering of the conduit to one side of the patella or top of the shoulder makes a substantial difference in providing flexible fit, form and function without compromise of effective fluid flow in all areas of the pad and consequent effectiveness of thermal therapy imparted by the pad. A pad with such members and conduit may be formed, for instance (but not necessarily) by introducing peripheral deep discontinuities, such as to overlie the proximal/distal axis of the patient""s limb in order to promote flexibility whether or not notions of symmetry are abandoned. According to one aspect of the invention, flexible therapeutic pads as viewed in plan accommodate multiple joints in a patient by including a first member, a second member in fluid communication with the first member through a conduit that is not substantially centered on the patella when the pad is applied for thermal therapy to the knee or the top of the shoulder when the pad is applied for thermal therapy to the shoulder, and an inlet and exhaust port communicating with one of the members so that the inlet and exhaust ports may be oriented generally on the limb (and thus not unduly cantilevered into midair) in a manner that allows: one of the first and second members to conform itself, at least partially, about a portion of the limb or body part on a first side of the joint onto which the other member is not conformed; (2) the other member to conform itself to the limb or body part on the other side of the joint; and, accordingly, (3) adherence of the pad to the joint in a manner that promotes effective contact while the joint is static and that permits the joint to flex without substantially disturbing the conformity of the pad members to the limb and body parts, while minimizing occlusion in the pad or areas of it, and thus without substantially comprising the comfort of the pad, the effectiveness of the heat transfer induced by the pad, and the flexibility and mobility of the patient""s joint.
The pads according to the present invention also may contain flow restrictions in order to regulate local thermal medium or fluid velocity at predetermined locations in order to regulate heat transfer rates locally within the pad. One or more flow path boundaries, formed by heat welding, bonding, or otherwise, create fluid flow paths within the pads. Such boundaries may be formed in a manner to reduce the flow path cross-sectional area in order to increase local fluid velocity and thus local heat transfer rate. Such flow path restrictions may occur according to the general dimensions of flow path channels created by such boundaries or additional flow path regulators such as spot welds or other structure. As a result, accentuated heat transfer rates may be induced at desired points within the joint such as directly medial and superior to the patella in an acute knee injury.
It is accordingly an object of the present invention to provide flexible therapeutic pads which are shaped to adhere to the knee joint and shoulder joint and surrounding limbs while static or throughout a broad range of motion, with minimum compromise of the flexibility, convenience and comfort.
It is an additional object of the present invention to provide flexible therapeutic pads which are shaped to adhere to the knee joint and shoulder joint and surrounding limbs while static or throughout a broad range of motion, with minimum tendency to form internal occlusion or blockage which would preclude or reduce fluid flow in a manner that substantially adversely affects fluid flow and effectiveness of thermal therapy imparted by the pad.
It is another object of the present invention to provide multijoint flexible therapeutic pads which eschew gratuitous notions of symmetry in favor of the need to introduce peripheral discontinuities along the proximal/distal axis of the patient""s limb in order to promote pad flexibility, joint flexibility and mobility, convenience, comfort and effective heat transfer induced by the pad.
It is another object of the present invention to provide multijoint flexible therapeutic pads which feature a number of members each of which may be attached and conformed to a separate limb portion or body part in the vicinity of the joint in order to promote flexibility, convenience, comfort and effective heat transfer.
It is another object of the present invention to provide a flexible therapeutic pad which is shaped and structured to accommodate the knee joint, the shoulder joint and other joints, and which departs from notions of symmetry previously manifested in conventional multijoint flexible therapeutic pads in favor of an asymmetrical shape that promotes flexibility of the pad and joint, increased comfort and convenience and more effective heat transfer.
It is an additional object of the present invention to provide a flexible therapeutic pad which is adapted in shape to accommodate a range of joints in the body with superior fit, form and function, and which can be manufactured inexpensively in order to be competitive in the changing marketplace.
It is an additional object of the present invention to provide multijoint flexible therapeutic pads which feature flow regulation structure at pre-determined points within the pads in order to regulate local fluid velocity, and, accordingly, local heat transfer rates at predetermined points within the joint or body part.
It is an additional object of the present invention to provide thermal therapy pads which are more likely to be employed by the patient over the full range of prescribed therapy because they are more flexible, comfortable and convenient than previously existing flexible therapeutic pads.
Other objects, features and advantages of the present invention will become apparent with respect to the remainder of this document.